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<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
 <script>
  //外层循环打印 第n天
  for(let i = 1;i<=3 ;i++){
    document.write(`第${i}天<br>`)
    //内层循环打印 第几个单词
    for(let j = 1; j<=5;j++ ){
      document.write(`记住了第${j}个单词<br>`)
    }
  }
 </script> 
</body>
</html>